A number of different devices for separating mixtures of valuable substances are known. It frequently is the case that certain valuable substances are to be separated from a mixture of valuable substances so that they can be subjected to further processing. However, there are also cases in which certain substances which render the further processing of the mixture difficult or even impossible are to be removed from the substance mixture.
When valuable substances are collected in bags or cardboard boxes and are automatically further processed by means of machines, the bags or cardboard boxes first have to be opened and, in most cases, then have to be removed from the substance mixture. Particularly in the case of plastic bags, recycling is often desired. Also larger foil portions in the substance mixture can be subjected to recycling. Thus, the problem presents itself that the packaging of the substance mixture, normally bags or cardboard boxes, is to be removed from the substance mixture. In this process, other substances, such as larger foil portions, should also be removed and cardboard boxes should be separated from the delivered paper.
The WO 95/07769 discloses a device for removing flat, light substances, such as plastic foils, comprising an air sifting. The substance mixture is conveyed by a conveyor belt to a discharge point and, when falling down, air is applied thereto by a blower. The air flow generated by the blower is dimensioned such that only light, flat materials are swept along by it, whereas heavier, more compact materials drop off the discharge point onto a second conveyor belt and are conveyed away by the same. The light, flat materials are swept along by the air flow to a discharge zone in which the materials descend with increasing distance from the blower and fall onto another conveyor belt by which they are conveyed away. Foils which do not contain any further substances and lie on top of the substance mixture can sufficiently be separated in this way. However, this device is not suitable for conveying away bag-like foils which still contain heavier substances, or foils which are at least partly buried by other substances.
It is the object of the invention to provide a device by means of which foils or cardboard boxes as well as similar substances and, if required, also other substances can specifically be removed from a mixture of valuable substances.
This object is achieved by the features of claim 1. According to the invention, a device for removing flat materials from a mixture of valuable substances comprises a conveying means by which the substance mixture is conveyed, and an extraction means for extracting the flat materials from the substance mixture in an extraction zone, with the extraction means comprising extracting prongs which are provided on a revolving transport means deflected at two points of deflection. The materials which have been picked up are discharged in a discharge zone.
Advantageously, the device can also remove smaller portions of foils or the like. The construction and setting-up of the device determines which material of which size is to be removed.
For discharging the materials, the transport means can be deflected at the two deflection points having a different deflection radius. The effect of this is that the extracting prongs are differently spread. This different spreading enables or facilitates the discharge of materials which have been picked up. Once the materials have been picked up by the prongs, they are, to a certain extent, stuck in the prongs. When the prongs move relative to each other, for example due to a spreading in the deflection point, the materials come off the prongs more easily, in particular, if the prongs are moved back again after the spreading, as is the case when they pass through the deflection point. It has proved to be of advantage to apply different deflection radii. When describing the Concrete embodiment, this will still be discussed in greater detail.
The dimensioning of the deflection radii has a considerable influence on the mode of operation of the device. The deflection radii do not only influence the spreading of the prongs but also the guiding of the prongs in the extraction zone. In the case of a large radius in the extraction zone, the extracting prongs are in contact with the substance mixture for a greater length of travel before being further transported. Of course, also the alignment of the prongs with respect to the substance mixture is influenced by the deflection radius and the arrangement of the deflection means Furthermore, if the deflection radius of the lower deflection means is large, the extracting prongs are deflected more slowly so that a smaller number of unwanted substances is picked up along with the materials to be extracted, since the materials are held for quite some time in a position in which the substances can drop. Bags, in particular, are held or transported for quite some time in a position which enables them to be emptied. On the other hand, by a fast deflection of the extracting prongs, the extracted materials, when being transported upwards, would quickly reach a position in which unwanted substances that have been picked up can no longer fall down.
The same effect can, of course, be achieved when the prongs are moved appropriately by some means. For instance, the prongs can be tilted by a tilting means or shifted by a shifting means.
Furthermore, for the discharge, a blower may be provided which is capable of blowing on the extracted materials through nozzles. These measures can also be combined with other described measures for discharging the materials. A plurality of nozzles may be provided at different positions. It has proved successful to arrange them in the area of the extracting prongs. A plurality of nozzles may be provided over the width of the transport means.
A plurality of nozzles may also be arranged in the transport direction. A whole array of nozzles may be provided so as to blow away the materials in the discharge zone. For realizing the nozzle arrangement, hollow bars having blow-out openings may be provided. These hollow bars extend over the width of the transport means or also alongside the transport direction, with an arrangement of the blow-out openings in the area of the prongs being basically advantageous, since the materials have to be separated from the prongs. Of course, such bars may also be arranged at an angle to the transport means.
The blow-out direction of the nozzles can be made to be adjustable. This adjustment may be provided individually for each nozzle or for a whole group of nozzles, e.g. by pivoting a nozzle bar.
For further conveying the discharged materials, it has proved successful to first guide them to a baffle plate so that they slide down this plate and are then conveyed on by a suction means or another conveying means, such as a conveyor belt.
A conveyor belt provided for the further conveyance may be inclined upwards in the transport direction so that materials which have been taken up but shall not be conveyed on slide down and are, for example, again supplied to the substance mixture. For further conveying the flat substances or materials to be conveyed away, the conveyor belt can be provided with knobs which may have a tapered tip.
For cleaning the extracted materials, a blower can be provided which blows on the materials through nozzles. For reasons of expediency, the nozzles are arranged behind the extraction zone. The nozzles can be arranged at different positions, and the blow-out direction of the nozzles can be adjustable so that blowing on the extracted materials can be effected as optimally and completely as possible.
The substances which have been blown off can fall down back onto the conveying means by gravity or can be sucked off by a suction means. However, these measures can also be combined and the substances can be separated in this manner. Then, the heavier substances fall down and the lighter substances, e.g. small rests of foils which initially adhere to the extracted materials, can be sucked off by a suction means and can be further processed. In this area, baffle sheets may be provided at which the heavier substances rebound, and only lighter substances are subjected to a removal by suction.
Removing the materials by suction can be assisted by the arrangement of nozzles and by the blowing out, e.g., of air. Due to this, the materials come off the transport means more easily and can be better sucked off.
Advantageously, the extracting prongs are pivotable. Pivoting can be effected via a pivoting means so as to improve the extraction and discharge of materials and to enable larger objects to pass, if required. However, it is also possible to use simple resilient prongs which pivot when a predetermined release force is applied so as to prevent the system from being damaged or blocked. This will still be elaborated on in the description of the figures. So-called resilient prongs can also be deflected to the side and can be used advantageously. The extracting prongs can be formed in a bent manner.
Furthermore, the extracting prongs or at least their tips may be designed in the form of a knife so as to slit open materials, such as foils, when they are being picked up. This also facilitates the discharge, since the materials can come off the prongs more easily when they do not cling to them.
The distance of the extracting prongs with respect to each other in the transport direction or transverse thereto can, just as the length of the prongs, be adjustable according to the demand made on the device. Different prongs may also be mountable at different positions so that the device can be adapted to different demands.
The extracting prongs may be straight, curved or they may have any other shape. A shape which is not straight and which is designed such that the materials are urged to the outside has proved to be of advantage. This will be explained in greater detail by means of an embodiment. Such an effect can, in principle, be achieved by a shape in which the outer portion of the prongs is, with respect to the inner portion, displaced against the transport direction, that is to say displaced backwards with respect to the transport direction. However, one could also imagine different designs which ensure that, when the prongs are moved by the substance mixture, this mixture, i.e. the substances or materials to be extracted, is urged outwards.
In the extraction zone, one or also a plurality of strippers may be provided which can be pivotable. Between stripper and extracting prongs passing by, there may be a predetermined distance which is adjustable, if required. Yet, the stripper may also overlap the extracting prongs passing by. In this case, however, either the extracting prongs or the stripper, and, if required, both elements have to be pivotable, or the path of the extracting prongs has to go past the stripper. By the stripper, unwanted substances which have been picked up along with the extracted materials can be stripped off.
Above the conveying means and in front of the transport means carrying the extracting prongs, a pivotable baffle sheet can be provided which may have prongs. It is the purpose of the baffle sheet to form an intake zone for the material to be extracted and to loosen the delivered substance mixture, if required, as well as to prevent foils and the like from getting entangled in the extraction zone. The height of the baffle sheet above the conveyor belt on which the substance mixture is delivered is advantageously adjustable. Also the distance of the baffle sheet from the transport means for conveying away the extracted materials is adjustable.
So as to prevent the device from being blocked when more solid, larger objects are delivered, the baffle sheet should make way when a predetermined force is exceeded. This can be achieved by a pivoting movement, but also by a linear guidance upwards.
It has proved successful if the transport means and the conveying means work in opposite directions and the delivered substance mixture in a way comes towards the extracting prongs.
In spite of the baffle sheet, the device could be blocked upon delivery of bulky materials, if these materials are seized by the extracting prongs but cannot be transported away. The likelihood of a blockage is reduced by resilient prongs which can give way. However, so as to ensure a more reliable, continuous operation of the device at all events, it is, in the case of the risk of a blockage, advantageous if, at least in the area of the extraction zone, the transport means can be moved from its normal position further away from the conveying means.
This can be achieved in that at least a part of the transport means is linearly moveable or in that at least a part of the transport means is pivotable. However, it is also possible that at least the whole transport means is pivotable.The device shall give way when a predetermined force is exceeded. If pivoting is realized, the pivot axis can be selected to be at a distance from the center of gravity such that the device is brought into its operating position by gravity, and the force causing the pivoting has to act against the force of gravity. The transport means, but also the holding-down appliance, can be pivoted by a suitable selection of the pivot axes due to the force built up by the delivered object alone. The elements to be pivoted may also be biased by springs.
However, also a control by sensors may be provided by which, upon detection of the risk of a blockage, at least a part of the device or the holding-down appliance is caused to move away from the conveying means by actuators.
The blowers used can generate a pulsating air flow or the air flow can be discharged by a pulsating means in a pulsating manner through the nozzles. The pulsation will particularly make flat materials vibrate and will thus enable them to come off more easily. Individual nozzles or nozzle groups are capable of being switched off and it may be possible to apply a pulsating air flow to certain nozzle groups and a continuous air flow to others. The cross section of the nozzles may have a round, slotted or cross-slotted shape. Also other cross sections can produce good results depending on the type of the materials.
Instead of the blowers or in addition to the same, a means for ejecting fluids can be employed. The effect achieved by the ejection of fluids, such as water, is basically the same as that achieved by the blowers. However, in addition, a cleaning is achieved and the materials are moistened, which may be desired for the further processing.
Individual nozzles or nozzle groups can, depending on the materials and the conveying task, be capable of being aligned and switched so that blowing can, for example, be effected only from selected nozzles at a predetermined angle.
In the embodiments described in the following, the device is designed to remove flat materials from a mixture of valuable substances. However, the device may also be used to additionally extract certain other materials, such as hollow bodies, from the mixture of valuable substances. For this purpose, the extraction means is set up such that also these materials are extracted and conveyed away. When the materials which have been picked up are discharged, a separation takes place which can be effected by a known air sifting but also by other methods. Frequently, the materials can already easily be separated by the different trajectories of the discharged materials.
The pick-up and discharge behavior of the device can be improved by the following features. The extracting prongs may, in their bottom portion, be provided with a covering so that only the tips of the extracting prongs project. This covering may be cylindrical or frustoconical. In the latter case, the portion having the larger diameter is provided in the root of the extracting prongs and the portion having a smaller diameter is provided in the upper portion of the extracting prongs. The covering may also be formed by a plate-like element and a subsequent tubular element. The covering may also be formed integrally with the extracting prongs. For reasons of expediency, the root portion of the extracting prong, in which a spring may be provided (resilient prong), is covered by the covering so as to prevent extracted materials from getting stuck in the root portion.
The covering achieves the effect described in the following. The materials which have been picked up rather remain in the upper portion of the extracting prongs, since their lowering is prevented by the step formed by the covering. The frustoconical shape furthermore has the effect that any materials which may have reached the bottom portion nevertheless can come off again more easily, since the clear space increases towards the top.
On the discharge side of the transport means, the device may have one or plural rotatable rolls or rollers at which objects dropping down roll off either clockwise or counter clockwise. In this manner, flat materials can be prevented from falling back onto the conveying means and can be further transported by the transport means. Due to the fact that the roll or roller is rotatably supported, objects cannot remain thereon. So as to reliably ensure further transporting of these objects by the extracting prongs and prevent them from falling back onto the conveying means, sheets and/or guides can be provided which may also be resilient or pivotable or also displaceable so as to reliably avoid blockage of the device. These sheets or guides may be provided with blade-like ripping means which contribute to a reduction of the materials in size or to the ripping open of closed objects. Such a construction will be described in greater detail by means of an embodiment.